An electrical switch of the kind concerned typically has a casing, a fixed contact and a moving contact, and an actuator for moving the moving contact into contact with the fixed contact. The actuator is movable to an opposite position for permitting the moving contact to move out of contact from the fixed contact under the action of a spring.
In a faulty situation, the moving contact may be hindered from departing from the fixed contact while the switch is intended to be opened. This may occur, particularly but not exclusively, when the load current is large and the two contacts are welded together as a result of arcing and/or flashover across them.
The invention seeks to provide an improved electrical switch of this type in general.
According to the invention, there is provided an electrical switch comprising a casing, a fixed contact and a moving contact in the scaning, and an actuator supported by the casing for movement to a first position thereby moving the moving contact into contact with the fixed contact. The actuator is movable to a second position for permitting the moving contact to move out of contact from the fixed contact. Resilient means biases the moving contact out of contact from the fixed contact. The switch includes a remover having a part provided adjacent the fixed contact and movable by the actuator moving to the second position for removing the moving contact from the fixed contact in case the moving contact stays in contact with the fixed contact.
Preferably, the remover part is provided on the same side as the fixed contact relative to the moving contact for pushing the moving contact away from the fixed contact.
It is preferred that the remover is supported for sliding movement to remove the moving contact from the fixed contact.
It is further preferred that the electrical switch includes a pivotal member provided between the actuator and the remover for pivoting by the actuator to slide the remover.
In a preferred embodiment, the electrical switch includes a contact lever having a first end about which the lever is pivotably supported and an opposite second end supporting the moving contact. The remover part is arranged to act upon the second lever end for removing the moving contact from the fixed contact.
More preferably, the remover part faces the moving contact as the fixed contact and is slidable in a direction substantially perpendicular to the contact lever for hitting its second end to push the moving contact away from the fixed contact.
More preferably, the electrical switch includes a pivotal member provided between the actuator and the remover for pivoting by the actuator to move the remover, the pivotal member extending substantially parallel to the contact lever.
More preferably, the electrical switch includes a pivotal lever having a first end for pivoting by the actuator and a second end for moving the remover. The actuator includes a slider slidable by the actuator through a cam action, and the slider is positioned between the first ends of the contact lever and the pivotal lever.
Further more preferably, the actuator includes an inclined slot through which the slider extends at substantially right angles, such that the slider will be slid by the actuator through a cam action in a direction substantially perpendicular to the direction in which the actuator moves.
In a specific construction, the resilient means comprises a first spring biassing the actuator towards its second position and a second spring biassing the moving contact away from the fixed contact.
As an example, the electrical switch is a normally-open pushbutton switch.